Field of the Invention
The present invention relates to an improved method for isolating nucleic acids, particularly genomic desoxyribonucleic acid (DNA) from blood.
Description of Related Art
Methods for the purification and isolation of nucleic acids, particularly genomic DNA, from whole blood are known from the prior art. Their method of application, however, has proved to be very complex and moreover very laborious and time consuming. Aside from this, the majority of methods, in addition to an isolation of the cell material or the cell nuclei, require a relatively long incubation time in the presence of proteinases, followed by—optionally several—phenol extractions (Molecular Cloning, A Laboratory Manual, Maniatis et al., pg. 9.17-9.18 as well as Nucl. Acid Res. 3, 2303-2306).
In view of these disadvantages, alternative methods have since been developed, which were intended not only to minimise the costs but also to increase the yield of nucleic acid or genomic DNA as well as their purity. Such methods are based on the use of chaotropic salts (Nucl. Acid Res. 15, 9611, 1987 as well as Anal. Biochem. 180, 276-278, 1989).
Thus, a method is disclosed, inter alia, in the European Patent Application EP 0 389 063, in which the blood sample under investigation is treated with a chaotropic substance in the presence of a matrix material—present in the form of particles—such as, for example silica. This was based on the knowledge that under these reaction conditions, the nucleic acids are liberated from the cells and then bind to suitable silica-based matrix materials. The matrix material possessing the nucleic acids can subsequently be separated from the reaction solution, e.g. by means of centrifugation. After separation of the supernatant liquid, the matrix material is subjected to one, or when necessary, a plurality of washing steps.
However, the above-described methods each have the disadvantages that they are very time consuming and include undesirable centrifugation steps that are inevitably linked to a material transfer that once again is laborious for each individual sample, and in addition is associated with a risk of contamination. In addition, these processes suffer the serious disadvantage that they cannot be automated.
Accordingly, the object of the present invention consists in avoiding the disadvantages of the methods from the prior art and provides a method for isolating nucleic acids, preferably genomic DNA, from blood, which in particular avoids time consuming and above all laborious centrifugation steps and which in particular can be automated. Moreover, the risk of contamination and the resulting biologically contaminated waste materials should be reduced to a minimum. In addition, the nucleic acids or the genomic DNA obtained in this way should be available in a form that makes them available for subsequent reactions—such as, for example, amplification reactions, particularly PCR—without additional process steps. This requirement stems from the need for genomic DNA for numerous different investigative methods such as e.g. genotyping, etc.